Abstract:This paper studies the optimization model and area coverage enhancement issues in wireless multimedia sensor networks (WMSNs). First, based on the directional perception characteristics of the multimedia sensor nodes, a modified sector-ring sensing model is provided to explore issues in video acceptable sharpness and regional coverage enhancement in WMSNs. Next, a mixed virtual potential field is proposed to enhance the area coverage in WMSNs through centroids movement under the effect of gravity and repulsion from the virtual potential field. To overcome the deficiency of local minimum and its reduced optimizing effect of coverage with traditional virtual potential field, the proposed algorithm improves the function of repulsion force by taking the common coverage rate of neighbor nodes into consideration to assist the adjustment of perception directions of the nodes. It also transmits border-dynamic repulsion force to sensor nodes after the iteration is completed to further optimize utilization of boundary nodes. Finally, a series of experiments and related simulations are performed to demonstrate the effectiveness of the algorithm.

Abstract:Hidden/exposed nodes are key factor which affects the reliability of broadcasting information and the MAC Contention Window is another factor which affects the throughput for single-hop broadcasting protocols in VANET. Firstly, this paper provides a theoretical analytic model to analyze the relationship among reliability, throughput, node density and Contention Window. Next, based on multi-object optimization theory, an adaptive reliability single-hop broadcast protocol (ARSB) is proposed. Simulation results show that ARSB not only enhances broadcast reliability and satisfies the broadcasting information real-time needs, but also optimizes broadcast throughput by adapting Contention Window of broadcasting nodes.

Abstract:One of the most crucial tasks in wireless sensor networks (WSN) is to determine the locations of sensory nodes as they may not all be equipped with GPS receivers. In this paper, an improved algorithm called Monte Carlo localization weighted by similarity (MCWS) is proposed. MCWS optimizes the sampling area of Monte Carlo localization (MCL) by adopting the mobile node's location based on the received signal strength indicator (RSSI) as the new sampling center. The signal values are stored as a target sequence, and by comparing the similarity between samples' sequences and the target sequence, samples can be filtered. Also the similarity values are used as the weighted standards to calculate coordinate of the mobile node. Extensive simulation results confirm that the new localization approach outperforms other MCL algorithms. The MCWS algorithm reduces the localization error by 1%~10% under different density of beacon nodes and by 30%~40% under different maximum speed of mobile nodes, respectively.

Abstract:Target tracking is one of the essential applications of the wireless sensor network. This paper considers the scenario where the target motion trajectory satisfies a quadratic equality constraint. In practice, when an aircraft hovers or a ground vehicle travels along a curve, its trajectory can be represented approximately as a quadratic function. This study applies quadratic constraints in the well-known Kalman filter (KF) to improve its performance in target tracking. The proposed algorithm first utilizes newly obtained positioning measurements and the unconstrained KF to produce an updated state estimation and then refines it using a maximum likelihood estimator (MLE) with quadratic equality constraints. When solving the constrained MLE problem, this paper formulates it as a generalized trust region sub-problem (GTRS) in order to obtain its globally optimal solution. Simulation results show that the proposed algorithm outperforms previously developed nonlinear KF algorithms with quadratic equality constraints in terms of enhanced target tracking accuracy.

Abstract:A localization algorithm for active-restricted 3-dimensional underwater sensor networks called LAR is proposed. It makes use of active-restricted sensor nodes' mobility to assist localization, and implements hierarchical mechanism to localize all the deployed sensor nodes. A compensation method for dynamic environment is also proposed based on the characteristics of mobile underwater sensor nodes. The obtained simulation results indicate that LAR is an effective scheme for underwater sensor network localization.

Abstract:Traditionally, sea cucumber production relies heavily on human labors which results in low production efficiency and inability to meet the demands of a rapidly growing market. To address this problem, this paper brings the idea of cyber physical systems (CPS) into aquatic areas. This paper provide a detailed analysis of the theory and characteristics of CPS along with its practical significance, and construct a physical information fusion system for sea cucumber production. The system is designed according to the CPS architecture, which includes the environmental monitoring subsystem, the information processing and transmission subsystem, the process control subsystem and the remote control center. In accordance with the characteristics of interaction between physics and information, this paper models and verifies the physical process by using the theory of automata, which ensures the reliability of the overall system. The deployment of the main parts of the system has been completed. The observation data indicates that, the system can be used to effectively monitor sea cucumber production. The system also has good scalability. Through in-depth cooperation with experts in the field, we believe it can be extended to be used in many other applications in water environment.

Abstract:Nowadays, low-carbon life and low energy consumption are popular topics as more and more people are looking for "green transport". With the rapid development of wireless communication technology and the widespread adoption of vehicles in daily life, Vehicular ad hoc Network (VANET), as a new research hot spot, has attracted much attention. This paper proposes a new method to analyze VANET and explain network behavior with its physical meaning. Firstly, this paper models the VANET based on the topology characteristics which will be analyzed based on the real data collected by more than 4 000 taxis in Shanghai. The topology characteristics include degree distribution, clustering coefficient, characteristic path length and so on. The statistical analyses show the degree distribution follows the power law which is the classic characteristics of scale-free network in complex networks. It also reveals high clustering coefficient of VANET. Through combining the complex network theory and applying the small world model and scale free model, The paper builds a VANET model and create external interface to control the network. The simulations prove the effectiveness of our model, which helps us to build capable simulation platform of VANET with better network control.

Abstract:It is an important research area in the Internet of Things (IoT) to maintain the communication continuity between the moving Mobile Nodes (MNs) in the IEEE 802.15.4 Low-power Wireless Personal Network (LoWPAN) and the Correspondent Nodes (CNs) in the IP network. In the existing mobile IPv6 protocols, such as MIPv6, HMIPv6 etc, some Signaling Packets (SPs) for mobility management have sizes larger than the maximum payload of the IEEE 802.15.4 MAC frame so that they are fragmented into multiple pieces carried in the LoWPAN, which increases the loss probability and the delay of the SPs. The proposed WPAN oriented MIPv6 (WoMIPv6) is able to reduce the sizes of the SPs to be less than 60 B using header compression technique so that the handoff caused by the MN crossing the boundary of two successive subnets is completed after a few small sizes of SPs are exchanged. In other words, each SP in the WoMIPv6 can be carried within a single IEEE 802.15.4 MAC frame without being fragmented. In addition, the delay in the WoMIPv6 is derived. Numeric analyses show WoMIPv6 performs better than HMIPv6 both in SP size and delay.

Abstract:This paper surveys the state-of-the-art researches of wireless cooperative relaying networks with network coding, investigates representative resource allocation strategies, and analyzes their features, performance and system requirements. It then discusses the effects of network coding, including digital network coding and physical network coding, in the design of resource allocation strategies for wireless cooperative relaying networks. As a result, a pragmatic system-level cross-layer optimization framework and associated core design principles are suggested. Finally, the future work of resource allocation for wireless cooperative relaying networks is presented, and some essential problems to be solved for final practical proposals are also addressed.

Abstract:The research of 3D underwater sensors' coverage-control has great significance in rational allocation of underwater space resources, environment-aware & information-acquisition and the network survivability improvement. In the real world situation, the uneven coverage is always needed in the underwater detection region. The current studies focus on the conception of "Event-Driven" without paying enough attention to the diversity of k-coverage requirements of different 3D regions. This work concentrates on the optimizational deployment for Underwater Sensor Networks' (UWSNs) diverse k-coverage requirements of distinguished regions. Based on the model of "buoys, anchors, underwater sensors which are connected and communicated via a wired cable with their respective buoy", we study the low-boundary number of the sensors required by diversity of k-coverage, and develop a novel algorithm: k-ERVFA (k-Equivalent radius virtual force algorithm) as an improvement to the classic virtual-force algorithm (VFA). Compared with the VFA in our simulation, the new algorithm only loses 1.21%~3.89% of 1-coverage rate in the required 1-coverage region, but significantly improves the 2- and 3- coverage rate to 17.42%~44.3% and 28.95%~49.53% respectively in the corresponding required coverage regions. The improvement in k-coverage requirements illustrates the correctness and effectiveness of k-ERVFA.

Abstract:Fingerprint localization is one of the most promising indoor positioning methods, and the fingerprint model based on the wireless signal strength is widely used due to its no-additional hardware cost and easy-to-spread characteristics. The selection of the fingerprint model is the key factor to the fingerprint positioning accuracy. Although the traditional fingerprint method by selecting the fingerprint collection points can reduce the computation, it contributes little to the accuracy of the positioning. In this paper, a fingerprint model based on principal component analysis is proposed. The new model accomplishes improvement in positioning accuracy as well as reduction in fingerprint calculation by selecting a set of "ingredients" with the largest impact on the accuracy to guide the positioning of fingerprint. Experimental results show that compared with the fingerprint algorithms based on Euclidean distance and nearest neighbor, the fingerprint algorithm based on principal component analysis improves average positioning accuracy to 2.7 m from 5.3 m and 3.9 m.

Abstract:Cryptographic approaches are vulnerable to impersonation attacks when nodes become compromised. Meanwhile, trust-based judgment and confirmation of cluster heads in WSN imposes higher communication cost. Trust management and authentication on cluster heads in WSN are essential in research on the mechanisms of secure data aggregation at present. In this paper, an energy attenuation model is adopted to describe event sensing in a kind of WSNs. Approximate evaluation on distance between occurring event and nodes within a cluster is achieved in case the location of the event is not known. Distribution properties of data points with clustering characteristics based on fitting curve construction are theoretically analyzed. In addition, the mechanism on trust authentication on cluster heads is also refined. Experimental results show that the proposed mechanism has much better performance on fitting accuracy and malicious CH recognition than previous works.

Abstract:In routing design in sensor networks, reliability and energy-efficiency are two important but conflicting performance metrics. To better reconcile the two metrics for different packet delivery requirements, utility model in economics is introduced, to integrate the cost and reliability metrics in a unified framework to evaluate the optimality of the routing decisions. This paper simultaneously optimize the transmission power in physical layer, the maximum retry count in MAC layer and the routing decisions in network layer using the framework provided by the utility model to achieve the objective of maximizing the expected utility of packet delivery. In the process, packets of different importance are delivered through different routing paths with different transmission powers and retry counts in each hop. Simulation results show that our cross-layer-optimized routing strategy performs better than those with fixed transmission power and fixed retry count. It also makes a good tradeoff among reliability, energy cost and the transmission priority.

Abstract:As application requirements evolve, the software on sensor nodes needs to be updated, or patched to fix errors to all the nodes of the entire networks. Recently, coding-based reprogramming protocols are proposed to provide efficient code dissemination in environments with high packet loss rate. Methods in analyzing the performance of these protocols, however, need further study. This paper presents an analytical model for energy cost based on time of dissemination and network topology. In this model, page pipelining and communication range between nodes are taken into accounts. Results from extensive simulations of a representative coding-based reprogramming protocol called Rateless Deluge coincide with the performance predicted by this model (the average relative error of single-node energy consumption is about 0.23%), thus validating the approach. These analytical results show that network density, network size and the number of packets per page all have significant impact on energy cost of the whole network. Particularly, a decrease in density of the network harms the energy performance (the energy consumption and network density is synthesized to be quadratic function). The energy cost of reprogramming the network is linear with the size of network (for the N×N grid network, the average growth rate is 50% when n change from 3 to 10) while the energy consumption of single node increases (the average growth rate is 6.9%). The energy cost is inverse with the page size of code image (the average rate of reduce is 11.2%).

Abstract:The delay tolerant network has been extensively studied and applied in recent years. When there is continuing and stable end-to-end path between the source node and the destination node in DTN, the traditional TCP/IP based network routing protocols cannot be applied to Delay/Disruption Tolerant Network. The storage-forward policy is used for message transmission. The performance of DTN routing protocols is influenced by the link existent time, buffer size of the nodes, and the mobility mode of the network. This paper discusses the study of DTN routing protocols, compare their performance, and highlight the future trends of DTN routing protocols.

Abstract:Seafloor observatory network has been an important data acquisition platform in marine scientific research. This pager provides a brief introduction to the history of seafloor observatory network system, followed by detailed description of the progress from the different countries round the world on seafloor cable observatory network systems. It also explores future development of the seafloor observatory network with a discussion on the key technologies and preliminary solutions employed in seafloor observatory network system.

Abstract:With the merging of quantum information and home network technologies, the adoption of quantum key to ensure the security of home network communication has become a critical topic. To address the problem of digital home network security with increased complexity and variety, this paper proposes a secure communication protocol in integrated quantum information technology in heterogeneous digital home network where GHZ states are shared by intelligent terminal equipments, family gateways and servers within business management platform. Based on the inherent triplet-state characteristics of quantum GHZ states, legitimacy of communications between servers within business management platform and intelligent terminal equipments can be validated, and information can also be protected. This protocol can be implemented by existing approaches.